Dental prosthesis support device and method of using same

ABSTRACT

A support device or post for fitting into an implant implanted into a patient which is configured to support a dental prosthesis is provided. An upper portion of the post, in one embodiment, has external screw threads for coupling a healing cap. The upper portion of the post may be removed or broken away at a weakened portion or constriction. The support device has a collar which can define various heights or diameters. The support device can be positioned in the implant by mating screw threads with the support device being torqued to a predetermined torque, preferably using a torque wrench which can be set using a non-variable, preferably gravity-based, standard.

This is a Divisional application of prior application Ser. No.08/707,416 filed Sep. 4, 1996, now U.S. Pat. No. 5,816,809 incorporatedherein by reference.

The present invention relates to a novel support device and system foruse in fabricating and supporting a dental prosthesis, and a novelmethod of installing the same into a patient, utilizing a previouslyimplanted hollow implant device.

BACKGROUND INFORMATION

Implant systems consisting of an implant or root portion embedded in apatient's bone or tissue and a post or support device for receiving aprosthesis are widely used. They are used most often in implantingpermanent teeth or crowns into the jawbones and surrounding tissue ofpatients.

Existing devices and methods often result in an incorrect fit of theprosthesis with the anchoring device and surrounding tissue. Anotherproblem with certain previous systems was the inability to fabricate aclosely fitting permanent prosthesis without time-consuming and unwieldyprocedures such as removing and reassembling the components of theimplant and post or fabricating a permanent prosthesis by takinglaborious and often inaccurate measurements of a temporary cap after theimplant, post and temporary cap had been installed in the patient.

Yet another problem in some implant devices was the tendency for the gumtissue (gingiva) to grow inward over the top of the implant beforeinstallation of the permanent prosthesis, so that the tissue had to becut away from the top of the implant before a prosthesis could besecured to the implant or post, thus resulting in trauma to the patientand ultimately a poor fit between the implant, post and prosthesis. Thepoor fit also resulted in food particles becoming wedged between theprosthesis and the cap or implant, leading to decay.

Another problem with certain previous implants was the inability to keepa support post firmly anchored in a receiving device already implantedin the patient's bone without cross-threading or stripping either orboth of the support post and receiving device.

Another problem with installing certain previous implant devices was thedifficulty associated with calibrating and applying a correct amount oftorque to the post so as to attach it firmly to the implant device,e.g., without rotating the implant device, and thus damaging ortraumatizing the patient and surrounding bone and tissue.

Certain previous torque wrenches for use with dental implant devicesdepended on the user noticing when slippage of the wrench occurredagainst the prosthesis or post. Some previous torque wrenches had alinear scale along their body to indicate the torque value set, whichwas hard to read. In spring-based wrenches the torque indication becameinaccurate as the spring constant of varied with use and/or metalfatigue. Utilizing other wrenches depended on the user's skill innoticing changes in the connection between the wrench and the implant orpost. This resulted in stripping the screw threads inside the implantwhen the practitioner's judgment was flawed, or rotating the implant andcausing patient trauma. In some designs, the wrench deformed when apredetermined torque was reached.

Many previous methods of calibrating a wrench to a specific torquerelied upon a variable, spring-based standard. This method had at leasttwo drawbacks: first, the torque amount varied as the spring experiencedmetal fatigue and/or eventual change in the spring constant, and second,the torque wrench typically could only be set infrequently. Manyprevious calibration devices for torque wrenches relied on complexmachinery to calibrate a measuring device which in turn was itself usedto calibrate a torque wrench, or alternatively relied on magnets tocalibrate torque.

Accordingly, it would be advantageous to provide a device for implantingand securing prostheses which results in a precise degree of fit betweenthe support device and the implant, the support device and thesurrounding tissue, and the support device and the prosthesis. It wouldbe advantageous to provide a method for installing the support deviceutilizing a non-spring based torque setting for a torque wrench forinserting the support device into the implant. It would also beadvantageous to provide a device for fabricating a permanent prosthesiswhose shape closely reproduced the support device for the prosthesis, soas to eliminate tedious measurements of the prosthesis in the patient'smouth, and provided for a more precise fit between the prosthesis andthe support device.

SUMMARY OF THE INVENTION

A novel and useful invention relates to fabricating and/or installing aprosthesis into patients. The prosthesis is usually a temporary healingcap or permanent dental crown. A hollow receiving device or "implant" isimplanted into a patient, usually into the patient's jaw bone(alveolar). A support device or "post" is fitted into the implant andextends upwardly away from the jaw bone for receiving a healing capand/or a permanent prosthesis.

In one embodiment, the support device has three portions, a distal rootportion, a middle collar portion and an upper post portion. The distalroot portion may additionally have external screw threads located abovea smooth lower surface. The distal root portion extends into theimplanted receiving device and is initially fitted into the receivingdevice by manually inserting the smooth end into the implanted receivingdevice. The smooth end functions as a lead so that the support deviceinitially fits loosely in the implanted receiving device but issubstantially axially aligned (e.g., to avoid cross-threading), awaitingtightening to a predetermined torque setting.

In one embodiment, various sizes of the middle collar portion areprovided to accommodate different tissue thicknesses and/or prosthesissize.

In one embodiment, the top of the support portion of the post has abreakaway feature effected by a weakened (e.g., lesser diameter)section. In yet another embodiment, the topmost portion of the post hasexternal threads which allow connection with a temporary healing cap.The healing cap may then be broken off prior to installation of thepermanent prosthesis without damage to the rest of the post, implant,bone or tissue. Alternatively, the permanent prosthesis may be seateddirectly on the healing cap.

In one embodiment of the invention, the uppermost portion of the post istapered to provide a secure fit with the prosthesis and lessen thepossibility of splintering of the prosthesis.

In one embodiment, the external surface of the upper part of the supportdevice has a hexagonal wrench-engaging surface. The surface may be usedto fit the post into the implant with a torque wrench. The surface maybe used by the practitioner to index the prosthesis to the post.

Another feature of the invention is the use of a replica of the post asa mold or analogue to fabricate a temporary healing cap or permanentprosthesis. This feature allows fabrication without dissembling andreassembling the post and/or implant from the patient's mouth andincreases the degree of fit and compatibility between the prosthesis andpost.

One embodiment of the invention utilizes a non-spring based torquewrench to install the support member. The wrench is set at apredetermined torque level using a non-spring, non-variable,weight-based calibration device and results in installation of thesupport device without rotation of the implant or damage to thesurrounding issue or bone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an implant, post, and prosthesiscoupled to a jaw bone according to one embodiment of the presentinvention;

FIG. 2 is an elevational view of a support structure according to anembodiment of the present invention;

FIG. 3 is a cross-sectional view of a healing cap according to anembodiment of the present invention;

FIG. 4 is an elevational view of an analog device according to anembodiment of the present invention;

FIG. 5 is a prospective exploded view of a torque wrench according to anembodiment of the present invention;

FIG. 6 is a prospective view of a torque setting-checking deviceaccording to an embodiment of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to a dental prosthesis device and method forinstalling same into a hollow implant 100 as shown in FIG. 1 which hasalready been embedded in the patient's bone 106. The implant device mayhave internal screw threads 102 and an interior upper surface 104. Theupper surface may be beveled, or smooth, flat and/or may have anexternal or internal slot or other shape for engagement by a driver suchas a slot or Philip's screwdriver, a hex or other wrench or the like.The implant 100 may be anchored in the bone 106 by screw threads, by apress or interference fit and the like. A number of implants can be usedincluding those available from Genetic Implant Systems, Inc. of Seattle,Wash.

As shown in FIG. 2, a support device or "post" has three portions, adistal root portion 200, a middle collar portion 202 and an upper postportion 204. The distal root portion is roughly cylindrical in shape andmay have external screw threads 206 located above a smooth lower surface208. Although the extent of the lower root portion of the post which isthreaded can be varied, in one embodiment at least about 3.5 mm of thepost is threaded. A number of materials can be used for making thesupport device. Including stainless steel, surgical steel, titanium ortitanium allow which may be coated with an HA coating. Other materialsthat can be used include composites such as fiber reinforced resins,ceramics, and the like.

In one embodiment, the middle collar portion 202 of the post defines asurface of revolution (although other shapes may be used such aselliptical or hexagonal in cross section) and has an outward flaringflange, of greater size (e.g., diameter 203) than either the lower 200or upper 204 portions of the post. In the depicted embodiment, theflange defines three angled surfaces, which are, from most distal tomost proximal, 210, 212 and 214 respectively. The lowermost or mostdistal portion of the flange 210 flares outward at a smaller angle 205relative to the horizontal than the angle 207 of flange surface 212. Theangle 205 is selected to provide a good seal with a surface of theimplant 100, such as being about equal to or slightly less than theangle of bevel 104. The first and/or second surfaces 210,212 may beprovided with one or more recesses, e.g., to accommodate an implantprotuberance, such as a driving surface. Angle 207 is determined by thedesired diameter 203 and collar height 211. Preferably many posts withdifferent diameters 203 and collar heights are available for the dentistto select among, e.g., to suit the tooth/jaw size and gum thickness ofthe patient. The uppermost or most proximal flange surface 214 slopesinward to the upper portion of the post 204, preferably at an angle 209of between about 0° and about 60°, more preferably, about 30°.

The upper portion 204 of the post may include a tapered region 213. Inone embodiment, the taper of the tapered portion of the post is betweenabout 2 and 12 degrees. Without wishing to be bound by any theory, it isbelieved that if the tapered portion is too sharply tapered, there canbe a retention problem. Providing that at least some taper is believedto be useful with drawing, fastening, crowns, and in situations in whichcrowns are splinted together. In one embodiment, the upper portion ofthe post has a weakened portion 216, e.g., a region of lesser diameterthan adjacent portions of the post. In the depicted embodiment, anexternally threaded region 217 is separated from the tapered portion 213by the constriction 216. The post may additionally have awrench-engaging external surface, such as a flat surface. In thedepicted embodiment, the tapered region 213 is hexagonal incross-section, to define six flat faces, e.g., for engaging ahex-wrench.

The distal root portion of the support device or post 200 is initiallyfitted into the implant 100 by manually inserting the smooth end 208into the threaded well of the implant. The smooth end 208 functions as alead so that the support device initially fits loosely in the implantawaiting tightening to a predetermined torque setting, but issufficiently axially aligned with the implant to substantially avoidcross-threading between screw threads 206 of the post and 102 of theimplant.

The support device or post is then tightened to a pre-determined torquesetting, e.g., by using the torque wrench 500 described below engagedwith the hexagonal outer surface 219 of the upper portion 204 of post200. Insertion of the post 200 into the implant 100 by this methodsubstantially avoids rotation of the implant 100, cross-threading orstripping of the internal screw threads 102 and trauma to the patient'sbone and surrounding tissue. Beveled surface 104 of the implantadditionally provides a closely fitting match with surface 210 of thesupport device.

In one embodiment, angle 205 is slightly less (such as about 1° less)than the angle of the implant bevel 104. The post 200 and/or implant 100have sufficient resilience and/or ductility that the torquedscrew-engagement of the post 200 and implant pull the post 200sufficiently tight against the upper surface 104 of the implant that thepost and implant are effectively in a sealing relation, substantiallypreventing entry of bacteria and/or tissue encroachment between the post200 and implant 100. In one embodiment, the angle 209 is about 30degrees. It is believed that providing at least some angle or bevel tosurface 214 is useful in order to make it easier to seat the prosthesisor crown.

After insertion of the support device or post 200 into implant 100, themiddle collar portion 202 defines an emergence profile 110 between thepost 200 and the surrounding tissue 106 at 110. The emergence surfacestarts at the top of the implant 100. The middle collar portion'sposition, surface and/or shape inhibit the growth of the surroundingtissue 108 into and over the top of the implant 100. The middle collarportion 202 may additionally have a variety of widths and thicknesses toaccommodate varying tissue thickness and prosthesis shape and size.

The upper flange surface 214 provides a close fit with the internal baseof permanent prosthesis 112, thus diminishing the possibility ofcreating an area between the prosthesis and post susceptible to foodparticle invasion, bacterial infection and decay.

A temporary healing cap 300 (FIG. 3) with internal screw threads 302 isfitted over post 200 by mating with the external threads 217 of post200. If desired, a temporary tooth prosthesis may be fabricated orattached to one extended surface 306 of one cap, e.g., for providing amore pleasing appearance during healing. Threading the temporary healingcap obviates the need for cementation of the temporary healing cap tothe post with its attendant risk of infection and irritation. Lowersurface 304 of the temporary healing cap is positioned adjacent tosurface 214 of the middle collar portion 202 of post 200, alsoinhibiting overgrowth of the surrounding tissue 108. Although, in thedepicted embodiment, the healing cap would have a lower rim which waspositioned at or above the gum line, if desired, the lower rim of thehealing cap could extend somewhat below the gum line. Although a numberof materials can be used for fabricating the healing cap, in oneembodiment, the cap is fabricated from or includes acrylic. In oneembodiment, both the post and the implant are comprised of titanium.

The temporary healing cap 300 may be removed by unscrewing, thus makingit possible to easily remove and, if desired, re-install the healingcap. The tip 222 of the post 200 may be removed, e.g. prior toinstalling the permanent prosthesis, by applying pressure to the top,thus causing breakage of the post top 222 at the weakened area 216. Thetip may also be removed by a wire cutter. Alternatively, permanentprosthesis 112 may be cemented to the post 200 without removing the tip222.

A permanent prosthesis or crown 112 may be affixed to the upper portionof the post 204, e.g. as depicted in FIG. 1. The external surface 219 ofthe upper portion of the post 204 serves to seat and fit the permanentprosthesis snugly on the post, and allows tile practitioner to index thepermanent prosthesis to the post. The angle of taper 224 of the taperedportion 213 is selected to provide sufficient holding or cementationsurface while accommodating minor post mis-alignment, e.g. in the caseof multiple splinted or coupled tooth prostheses. The angle 224 ispreferably less than about 10 degrees and is more preferably about sixdegrees.

Referring to FIG. 4, another aspect of the invention involves a replicaor analogue 400 of the upper portion 228 of post 204 e.g. for use infabricating a permanent prosthesis 112. The analogue 400 may have ahexagonal outer surface 402 to match the external surface 217 and upperflange surface 414 defining an angle and diameter similar to the angle209 and diameter 203 of the installed post 200. While the tissue andbone are healing after positioning the implant 100, the practitionerwill take an impression from the patient's mouth. The practitioner maythen make a mold from the impression and insert the analogue 400 intothe mold.

The practitioner can then use the combination of the analogue 400 andits relation to surrounding teeth and tissue as indicated by the mold tofashion a permanent prosthesis 112 which will comfortably fit into thepatient and will have a recess having a shape exactly matching the shapeof the upper portion 228 of the installed post. The fabrication is donewithout the need to dissemble and reassemble the post from the implantand also minimizes the need to reshape the prosthesis e.g. because offailure to initially fit into the patient.

Referring to FIG. 5, a torque wrench has an annular head 500 with anopening 502 into which is fitted a hollow shaft 504. An adjustableratchet head 506 fits into head and is secured in the head by aretaining ring 508. Ratchet head 506 has a square opening 524 forengaging a square drive of a hexagonal socket (not shown) configured toengage the post 200. A plunger 510 tapered at one end 512 is insertedinto shaft 504 so that end 512 contacts the external teeth 522 ofratchet head 506. The upper end of plunger 510 is fitted into the lowerportion of a hollow handle 514. The hollow handle 514 may be attached toshank 504 by a threaded surface 516. A spring 518 held in place by a setscrew 520 is inserted into handle 514 above plunger 510 covered byattaching cap 522. The plunger 510 is urged by the spring 518 towardsthe ratchet head 506 so that the pointed end 512 engages between teeth522 of the ratchet head. This engagement resists rotation of the ratchethead 506 with respect to the annular head 500 about the torque axis 528so that rotation of the shaft 504 about axis 528 causes rotation of theratchet head 506 (and, thus of any attached socket). This resistance torotation of the ratchet 506 with respect to the annular head 500 can beovercome. If there is sufficient torque being transferred from theratched head 506 to the driven object (e.g. because the driven object isrelatively well-seated, or otherwise resists further rotation), attemptsto rotate the annular head 500 with a greater torque will cause thepoint 512 to ride or cam up the side of a tooth 522, compressing plunger510 against the urging of the spring 518 and causing relative rotationor slipping of the ratchet 506 with respect to the annular head 500.Thus, the maximum amount of torque that can be transferred from thewrench to the driven object, before slipping occurs, depends on theamount of spring force, and thus the amount of compression of the spring518. This amount of spring force (and thus the maximum torque developedby the wrench) can be adjusted by rotating the handle 514 in direction532 to adjust the amount of spring compression.

Although it would be possible to mount a scale on the shaft 504 bearingindicia of the amount of torque, Such a scale is believed to beunreliable for may applications because the amount of spring forcedeveloped by the spring 518 will change through time because of metalfatigue or other aging effects. For this reason, according to oneembodiment of the invention, a separate calibration device is providedfor setting the torque of the wrench, preferably using a non-variablestandard, such as the force of gravity.

Referring to FIG. 6, a calibration device 600 has a frame 602 to which abeam member 604 is pivotable with respect to the frame about a pivotpoint 606. A weight 608 is attached to and movable along the beam member604, and may be positioned according to a scale marked in torque units,e.g. newton-centimeters. A rigid gear arm 610 pivotable about axis 622intermeshes with a gear coupled to the beam 604 at pivot point 606. Apost 614 is rigidly attached to arm 612 such that rotation of post 614rotates arm 610 moving arm teeth 624, rotating gear 626 and pivotingattached beam 609, against the urging of weight 608. The amount oftorque applied to post 614 which is sufficient to lift beam 604 dependson the linear position of weight 608. Since the torque is set by agravity standard, it will be substantially non-variable and, inparticular, will not degrade as a result of a change in a springconstant.

The torque wrench is calibrated to a non-variable standard by firstsetting weight 608 to a specific torque. Ratchet 506 is then fitted overpost 614. The handle 514 is initially positioned with the lowestpossible torque setting thus initially the torque wrench will slip andthe beam 604 will not be lifted. Handle 514 is then rotated slightly toincrease the torque setting of the wrench and the wrench is used toattempt to rotate the post 614 and lift the beam 608. If the torquesetting to the wrench is too low to permit the torque wrench to rotatethe post 614, the handle 514 is rotated further, to further increase thetorque setting of the wrench and the wrench is again applied to the post614. By repeating this process, the torque wrench is adjusted until theavailable maximum torque is just sufficient to rotate the post 614 andlift the beam 604, at which point the torque wrench has been adjusted tothe torque indicate by the position of the weight 608 on the torquescale of the beam 604. The torque wrench is now calibrated tc the torquesetting selected and may be used, e.g. to fit the support device 200into implant 100 by engaging and rotating the hexagonal outer surface217 of the upper post member.

In use, alter the practitioner has drilled and tapped an appropriatesize recess in the patients jawbone 106 and inserted the implant 100,the practitioner selects a post among a plurality of available posts,having a desired color depth 211 (e.g. matching the thickness of the gumtissue 108) and a desired diameter 203, e.g. select to provide desiredstability for the prosthesis 112, yet avoid disability of the colorafter the prosthesis is positioned. The practitioner then inserts thesmooth portion 208 of the host 200 into the threaded well of the implant100 thus achieving desired axial alignment of the post 200 with the axisof the implant 100 so that the post threads 206 are sufficiently axiallyaligned with the implant threads 102 to avoid cross threading. The post200 is then rotated to engage the post threads 206 with the implantthreads 102. Initial rotation may be by hand or with a wrench. In thefinal stages of insertion, it is desired to provided a predeterminedamount of torque such as about 30 newton-centimeters. Preferably, thepractitioner adjusts a torque wrench such as the wrench depicted in FIG.5, using a calibration device such as the device of FIG. 6 to set thetorque wrench at the desired maximum torque. The practitioner thencouples a socket to the ratchet portion of the torque wrench and engagesthe socket with a wrench engaging surface of the post, such as one ormore flat surfaces, e.g. surfaces 209. The practitioner then uses thewrench to rotate the post 200 to the desired torque with respect to theimplant 100 drawing surface 210 tightly and in sealing relation to thetop of the implant 104. The practitioner then aligns the thread of ahealing cap (FIG. 3) with threads 217 on the top of the post and rotatesthe healing cap to engage the healing cap with a post 200 and seat thebottom surface 304 of the healing cap against the upper flange 214 ofthe post. If desired, a temporary tooth prosthesis may be cemented overthe healing cap.

The practitioner will take an impression of the patient's mouth eitherbefore installing the healing cap or at a later time, after (possiblytemporarily) removing the healing cap. The impression is used asdescribed above and typically by a technician, in combination with apost analog device as a guide for pouring a prosthesis which will havean exterior and interior shape such that when mounted on the installedpost the prosthesis will have the desired position and external shape.Because the installed post includes a flat portion or other wrenchengaging surface, the analog device will contain a similar surface andthus when the analog device is used as a part of the mulled or form inwhich a cast is made, the hollow portion of the prosthetic tooth willcontain a mating flat portion or wrench engaging surface. The matingrelationship of the flat surface of the prosthetic and the flat surfaceof the installed post permits the practitioner to index the prosthetictooth post in order to achieve the desired alignment when the prostheticis installed.

Although it would be possible to produce a prosthesis without using ananalog, it is believed that using the analog provides the advantage ofestablishing a nearly perfect margin for the prosthesis form as opposedto relying solely on an impression (without using an analog) which canhave an imperfect margin, e.g. in regions where tissue has moved orfallen in.

After desired healing has occurred, the practitioner will remove thehealing cap (and temporary prosthesis) if any and may, if desired,remove the tip 222 by breaking or cutting at the constriction 216. Theprosthesis formed as described above is then cemented to the taperedportion 213 of the post and the procedure is complete. One prostheticrestorative procedure which can be used includes the following steps. Ahealing cap is placed onto the implant at the time of implantuncovering. A post is placed into the healing plant at the time ofimplant covering or upon removing a healing cap. The post is secured tothe implant with a torque wrench and a post cover is threaded on orcemented on. An impression of the post is made. A post analog is placedinto the impression, secured to the impression, and a model is poured. Acrown is fabricated using the removable dye with post analog. The postcover thread is separated from the top of the post. The crown is tied onand cemented on the post using convention and bridge techniques. Amongother advantages, the present invention permits fabrication of the crownusing standard crown and bridge techniques and requires no specialtraining for restorative dentistry. The invention requires little in theway of additional restorative instrumentation, provides for low costsfor restorative components, allows the practitioner to use a normaldental laboratory for preparation of the crown or other components,requires only small or minimal restorative "chair" time, providesreliable predictable results, provides temporary coupled superstructuresthat result in a passive bit, achieves smooth contours and margins forbetter periodontal health and maintenance, provides cosmeticallypleasing appearance for the patient and increases patient satisfaction.

In light of the above description, a number of advantages of the presentinvention can be seen. The risk of cross-threading or stripping thescrew threads of either the implant or the post is reduced oreliminated. The practitioner is provided with the ability to chooseamong a variety of post collar shapes for receiving a dental prosthesisto accommodate both variations in vertical thickness of the gum tissueand various sizes of prosthesis. The ability to customize the supportdevice increases the degree of fit and comfort of the prosthesis as wellas minimizing the chance for bacterial infection and/or decay because ofloose fit of the prosthesis.

Size can be selected to define an emergence profile which starts at thetop of the implant device, and extends out into the surrounding tissue,thus prohibiting the tissue from growing over the top of the implantdevice and distorting the fit between the implant, post and prosthesis.The threaded top for the post, allows a temporary healing cap to bethreaded to the post rather than cemented, and facilitates removal ofthe temporary cap and, if desired, reinstallation. A wrench-engagingsurface allows the post to be firmly and snugly fitted into the implantdevice by means of engaging a torque wrench set at a predeterminedtorque setting. The predetermined torque setting and its application toinstallation of the post are effected without rotation of the implantdevice or trauma to the surrounding bone and tissue. Preferably one ormore surfaces of the post can be used for both a wrench engaging surfaceand an indexing surface. A replica or analogue of the support deviceallows the practitioner to fabricate a permanent prosthesis withoutdissembling the support device from the patient. A calibration deviceallows the practitioner to directly calibrate a torque wrench by using anon-variable weight standard. The calibration device does not rely on aspring-based scale, and thus avoids the usual problems associated withmetal fatigue and change of the spring constant through time and use.

A number of variations and modifications of the invention can be used.The invention is not limited to periodontal applications, and may beused to implant and fashion prostheses and the like into other bones ortissue. The amount and degree of threading on the lower portion of thesupport device can be varied; deeper implants may require more threadson the support device. Also, variations in the middle collar portion ofthe support device, and particularly the shape and slope of the flangesurfaces, may be varied to accommodate tissue thickness and prosthesissize. In one embodiment, the post is driven to the implant with a torqueof between about 30 to 40 newton-centimeters. Although in the depictedconfiguration, the angle 207 is shown to be about 65 degrees, otherangles can be used depending on the desired thickness 211 and diameter203, such as angles between 10 and 90 degrees providing a screw-typeattachment for coupling the healing cap is advantageous because it canbe coupled in a quick efficient manner and avoids the potential forproblems arising with the use of cement in the vicinity of an openwound. By providing a non-variable torque wrench calibration device,which is quick and simple to use, it becomes easier for the practitionerto calibrate the wrench with high frequency, such as for everyprocedure, or multiple time during a procedure to insure providing theproper torque by providing a slip-type torque wrench with adjustabletorque, which is manually driven, the practitioner received a tactilefeedback which can be useful in avoiding overdriving the post and of atype which is available for an electrically or otherwise automaticallydriven torque device. Preferably the torque wrench is adjusted withoutreliance on the spring-based scale such as a scale located on the torquewrench handle (or other portion of the torque wrench). Thus in oneembodiment, the torque wrench contains no torque scale on the wrenchitself. In another embodiment, an approximate torque scale may beprovided for initial adjustment to a torque value close to the finaldesired torque value before final adjustment of the torque using acalibration device. Preferably, the torque wrench is adjusted to atorque of between about 28 and 34 newton-centimeters, more preferablyabout 30 to about 32 newton-centimeters. In the depicted embodiment, thepost 200 establishes an emergence profile beginning immediately at thetop of the implant 100. As depicted in FIG. 2, the diameter 203 of thecollar region is located at the depicted embodiment at the margin of thecrown 112. The post 200 can be provided with a variety of thread sizesand shoulder shapes, e.g. to accommodate or bypass shapes at the upperportion of the implant 100 such as external hexes and squares, internalhexes and squares, and octagons and similar implant drive devices. Thecap is useful in keeping tissue 108 from collapsing in over the shoulderof the post. If desired, the cap can be relined with acrylic allowing itto be cemented on the post when a temporary crown is formed as part ofthe healing cap. By using the analog device, laboratory crownfabrication procedures can be followed without needing to remove thepost from the mouth. The analog device fits into a flexible impressionof the post in the mouth and provides a precise die on which a crown canbe fabricated. Thus, a perfect impression of the margins of the shoulderin the mouth is not essential since the analog provides the technicianwith a perfect metal margin to work with. In one embodiment, collar isprovided in a plurality of heights in increments e.g. of 1 mm so thatregion 211 may be a height of 1 mm, 2 mm, 3 mm, 4 mm, etc. The diameter203 may be in a diameter preferably between about the outer diameter ofthe implant 100 and about 7 mm (or more). In one embodiment the lowerportion diameter 232 is about i.95 mm, the lower portion height is about2 mm, the upper root portion height 236 is about 3.7 mm, the lower flareangle is about 30 degrees, the upper bevel angle 209 is about 30degrees, the constriction diameter 216 is about 0.63 mm, the top height238 is about 1.6 mm, the top diameter is about 1.5 mm, the width of thepost at the lightest portion of the taper region 242 is about 2.95 mmand at the top of the taper portion 244 is about 1.5 mm. In oneembodiment, the height 306 of the healing cap is bout 3.6 mm and thediameter is selected to match the collar shoulder diameter 203. In oneembodiment the lower portion 406 of the analog 400 is provided withknurled services 408 to assist in handling the device.

The tapered shape of the upper portion of the support device need not betapered from the top of the post to the collar. It may be tapered onlyat one or more portions, e.g. to accommodate variations in theprosthesis and the degree of interconnectability required withsurrounding teeth and/or prosthesis.

The emergence profile or surface may vary e.g. according to whether thepractitioner is dealing with front or back teeth.

What is claimed is:
 1. A torque wrench for use in installing andpositioning a support member for a dental prosthesis in an implantdevice positioned in a patient, which comprises:a hollow annular head; acircular ratchet device retained in said head; a hollow shaft having afirst end and a second end, the second end coupled to said head; aplunger of lesser circumference than said shaft, having a tapered end,said plunger mounted in said shaft and engaging said ratchet device withsaid tapered end; a handle; a spring coupled to said handle and saidplunger, said handle connected to said shaft so that movement of saidhandle will adjust the compression of said spring against said plunger.2. A torque wrench as claimed in claim 1 wherein said torque wrench isprovided in the absence of a torque-indicating scale on said wrench. 3.A torque wrench, as claimed in claim 1, wherein said ratchet isrotatably mounted in said head and wherein said tapered end of saidplunger cams up a tooth of said ratchet to permit rotation of saidratchet in said head if a rotational torque applied to said ratchet isat least sufficient to impart a force to said plunger sufficient toovercome a force supplied by said spring.
 4. A torque wrench for use ininstalling and positioning a support member for a dental prosthesis inan implant device positioned in a patient, which comprises:head means; aratchet retained in said head means; shaft means having a first end anda second end, the second end coupled to said head means; a plunger,coupled to said shaft means, having disengagable ratchet engagementmeans; spring means coupled to said plunger; means for adjustingcompression of said spring against said plunger.
 5. A torque wrench asclaimed in claim 4 wherein said torque wrench is provided in the absenceof a torque-indicating means on said wrench.
 6. A torque wrench, asclaimed in claim 4, wherein said ratchet is rotatably mounted in saidhead and wherein said engagement means disengages from said ratchet topermit rotation of said ratchet in said head if a rotational torqueapplied to said ratchet is at least sufficient to impart a force to saidplunger sufficient to overcome a force supplied by said spring means. 7.A method for fabricating a torque wrench wherein said torque wrench isfor use in installing and positioning a support member for a dentalprosthesis in an implant device positioned in a patient, the methodcomprising:positioning a circular ratchet device in a hollow annularhead; coupling a shaft to said hollow annular head; coupling a plungerto said shaft, said plunger having a tapered end, said plunger coupledto said shaft so as to permit engagement with said ratchet device;coupling a spring to contact said plunger; coupling a handle to saidshaft such that movement of said handle will adjust compression of saidspring against said plunger.